Complementary Copper-Catalyzed and Electrochemical Aminosulfonylation of O-Homoallyl Benzimidates and N-Alkenyl Amidines with Sodium Sulfinates

CCl4-Induced Synthesis of Phosphonothioates, Sulfoxides, and Sulfones from Sodium Sulfinates

An external reductant-free and acid-free synthesis of phosphonothioates from odorless sodium sulfinates induced by CCl4 (1.0 equiv) under mild conditions has been achieved. This transformation provides an efficient synthetic approach to phosphonothioates in up to 98% yield with good functional group compatibility. In addition, an unexpected CCl4-induced synthesis of sulfoxides and sulfones from sodium sulfinates using DMSO as the solvent has been developed.

Electrochemical Oxidative Cascade Cyclization of Alkenyl Alcohols with External Nucleophiles to Access Amino- and Hydroxy-Functionalized O-Heterocycles

A convenient electrochemical oxidative cascade cyclization of alkenes equipped with pendant alcohols with general nucleophiles was developed. Using readily available diarylmethanimine and carboxylic acids as nucleophilic sources, a broad range of internal alkene and terminal alkene substrates could produce RCO2- and Ar2CN-functionalized O-heterocycles in moderate to high yields without the requirement for external oxidants and metals. These resulting products can subsequently be hydrolyzed to yield valuable NH2- and OH-functionalized tetrahydrofurans and tetrahydropyranes under mild conditions. Importantly, the efficient conversion of secondary alcohol products to amines with complete inversion of configuration enhances the methodology, enabling the construction of 2-aryl-3-amino tetrahydrofuran with high and complementary diastereoselectivity.

A Multicomponent [2+2+1] Cascade Cyclization to Synthesize Thiazol-2(3H)-one

A multicomponent [2+2+1] tandem cyclization of alkynones with amines and water using potassium thiocyanate as electrolyte and raw material to access thiazol-2(3H)-ones has been developed. This transformation proceeded smoothly via electrocatalytic oxidative C-H bond thiolation, and nucleophilic cascade cyclization to build the (C-S/C-N) bonds to construct the C-O bond. The reaction avoided using transition metal catalysts or oxidation reagents, making it more sustainable and renewable.

Electrochemical Ring-Opening of Cyclopropylamides with Alcohols toward the Synthesis of 1,3-Oxazines

An electrochemical method is presented to construct 1,3-oxazines by the oxidative ring-opening of cyclopropylamides with alcohols. This method avoids the use of external oxidants and thus shows good functional group tolerance. The substrate scope covers primary, secondary, and tertiary alcohols as well as (hetero)aryl amide-substituted cyclopropanes.

Cascade Electrochemical Aerobic Oxygenation of 2-Substituted Indoles and Electrochemical [5 + 3] Annulation with Amidines: Access to Eight-Membered Benzo[1,3,5]triazocin-6(5H)-ones

The cascade electrochemical C3-selective aerobic oxygenation of 2-substituted indoles and electrochemical [5 + 3] annulation with amidines through an undivided cell galvanostatic method employing molecular oxygen and "electricity" as green oxidants was developed. This protocol provides an efficient and direct approach to eight-membered benzo[1,3,5]triazocin-6(5H)-ones. Mechanistic studies suggested that two subsequent electrochemical processes both proceeded through radical pathways.

Photocatalytic 1,2-Iminosulfonylation and Remote 1,6-Iminosulfonylation of Olefins

A new class of iminosulfonylation reagents were developed and extensively used in the 1,2-iminosulfonylation of various olefins. Olefins containing bioactive molecules, such as indomethacin, gemfibrozil, clofibrate, and fenbufen, afforded the desired iminosulfonylation products in synthetically useful yields. Furthermore, the first remote 1,6-iminosulfonylation of alkenes was realized by using oxime ester bifunctionalization reagents. Overall, more than 40 structurally diverse β-imine sulfones were obtained in moderate to excellent yields.

Electrochemically Enabled Intramolecular Amino- and Oxysulfonylation of Alkenes with Sodium Sulfinates to Access Sulfonylated Saturated Heterocycles

A practical and efficient electrochemical intramolecular amino- or oxysulfonylation of internal alkenes equipped with pendant nitrogen or oxygen-centered nucleophiles with sodium sulfinate was developed. Under undivided electrolytic cell conditions, a variety of sulfonylated N-heterocycles and O-heterocycles, such as tetrahydrofurans, tetrahydropyrans, oxepanes, tetrahydropyrroles, piperidines, δ-valerolactones, etc., were efficiently prepared from easily accessible unsaturated alcohols, carboxylic acids, and N-tosyl amines without the need for additional metal or exogenous oxidant. The robust electrochemical transformation features excellent redox economy, high diastereoselectivity, and broad substrate specificity, which provide a general and practical access to sulfone-containing heterocycles and would facilitate the related synthetic and biological studies based on this electrosynthesis.

Visible-Light-Mediated Three-Component Cascade Sulfonylative Annulation

Visible-light-promoted cascade radical cyclization for the synthesis of sulfonylated benzimidazo/indolo[2,1-a]iso-quinolin-6(5H)-ones has been reported. The reaction provides transition-metal-free and expeditious access to sulfonylated polyaromatics. The use of sodium metabisulfite as a SO₂ surrogate and the rapid generation of molecular complexity using a three-component photochemical protocol are the salient features of this reaction manifold.